JP2014091666A - Gas treatment method and gas treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove a volatile material from dust that is separated from effluent gas discharged from cement firing equipment, and supplied to firing equipment; and to maintain a content of a volatile material that circulates in cement production equipment to a desired value for long-term, and to use the same to cement production equipment in general-purpose.SOLUTION: A gas treatment method further includes a volatile material removing process in which a volatile material is removed from dust collected in a dust collection process, the dust collection process includes: a first dust collection process in which dust is collected from effluent gas using an electrical dust precipitator; and a second dust collection process in which dust is collected from effluent gas after the first dust collection process, and the volatile material removing process removes a volatile material from dust collected in the second dust collection process.

Description

  The present invention relates to a gas processing method and gas processing equipment for treating exhaust gas discharged from a cement firing facility, and more particularly, to removing volatile substances from exhaust gas.

  Dust (powder derived from unreacted cement raw material, fuel, etc.) is contained in the exhaust gas discharged from the cement firing facility (consisting of a kiln, calciner, preheater, etc.). Such dust is collected in the dust collection process and separated from the exhaust gas, and then at least a part of the dust is returned as a cement raw material to the firing facility.

  In addition, the exhaust gas discharged from cement firing facilities contains relatively volatile substances (heavy metals such as mercury and thallium, chlorides of these heavy metals, and organic compounds such as toluene and benzene). There is a case. Specifically, in recent years, various wastes (incineration ash, various sludges, waste plastics, waste oil, etc.) have been used as cement raw materials and calcined fuels. For this reason, there exists a possibility that the volatile substance contained in the waste may also be contained in the cement raw material and the fired fuel. And by using such a cement raw material and a baking fuel, since a volatile substance volatilizes with the heat | fever of a baking equipment, a volatile substance will be contained in waste gas.

  Moreover, a part of volatile substance in exhaust gas is contained in the dust separated from the exhaust gas. Specifically, the temperature of the exhaust gas discharged from the firing facility is lowered through a path discharged into the atmosphere. At this time, a part of the volatile substance in the exhaust gas adheres (precipitates) to dust in the exhaust gas (particularly, dust having a relatively fine particle size in the particle size distribution of the dust in the exhaust gas). Thereby, a volatile substance will be contained in the dust separated from the exhaust gas in the dust collection step (particularly, dust having a relatively fine particle size in the particle size distribution of the dust in the exhaust gas).

  By the way, in recent years, it has been required to reduce the content of volatile substances in exhaust gas in order to reduce the amount of volatile substances discharged into the atmosphere. As a method for reducing the content of volatile substances in the exhaust gas, for example, an electric dust collector is installed in a route (exhaust gas route) until the exhaust gas discharged from the firing facility is discharged into the atmosphere. A method has been proposed in which a vertical raw material mill to which cement raw material and exhaust gas are supplied is installed upstream of the exhaust gas path (see Patent Document 1).

  In such a method, when the content of volatile substances in the exhaust gas discharged to the atmosphere exceeds a threshold value, the number of revolutions of the separator in the vertical raw material mill is increased, and the vertical raw material mill is discharged together with the exhaust gas. The particle size of the discharged cement raw material and dust is made relatively fine. Thereby, the adhesion (precipitation) amount of the volatile substance to the cement raw material and dust discharged from the vertical raw material mill increases, and the content of the volatile substance in the exhaust gas is reduced.

  Further, in such a method, cement raw material and dust discharged from the vertical raw material mill are supplied to the electric dust collector. Thereby, the cement raw material and dust are separated into a relatively coarse one and a relatively fine one. And when the content of volatile substances in the exhaust gas discharged into the atmosphere exceeds the threshold value, the amount of return of relatively fine cement raw materials and dust (which easily adheres to volatile substances) to the firing facility Decrease or stop returning. Thereby, since the quantity of the volatile substance circulated within the cement production facility is temporarily reduced, the volatile substance in the exhaust gas is maintained at a desired content.

JP 2011-241112 A

  However, in the method according to Patent Document 1, since the cement raw material and dust to which volatile substances are attached (deposited) are supplied to the firing facility, the volatile materials are volatilized again by the heat of the firing facility and are contained in the exhaust gas. Will be. In other words, when the cement raw material is continuously fired, the amount of volatile substances circulating in the cement manufacturing facility increases with time. For this reason, it becomes difficult to maintain the content of the volatile substance in the exhaust gas at a desired value in the long term.

  Further, the method according to Patent Document 1 requires a vertical raw material mill that simultaneously performs drying and pulverization of the cement raw material using the exhaust gas from the cement firing facility, so that the drying of the cement raw material is performed instead of the vertical raw material mill. It is difficult to adopt a configuration (for example, a combination of a rotary dryer and a tube mill) that performs pulverization and pulverization separately, and lacks versatility.

  Therefore, the present invention can efficiently remove volatile substances from the dust separated from the exhaust gas discharged from the cement firing equipment and supplied to the firing equipment, and the volatile substances circulating in the cement production equipment. It is an object of the present invention to provide a gas processing method and a gas processing facility that can maintain the content at a desired value in the long term and can be used for a general purpose in a cement manufacturing facility.

  The gas treatment method of the present invention includes a dust collection step for collecting dust in exhaust gas discharged from a firing facility for firing cement raw material, and at least a part of the dust collected in the dust collection step is used as cement raw material. A gas treatment method for supplying to a firing facility, further comprising a volatile substance removing step for removing a volatile substance from the dust collected in the dust collecting step, wherein the dust collecting step uses an electric dust collector. A first dust collecting step for collecting the dust from the first dust collecting step and a second dust collecting step for collecting the dust from the exhaust gas after the first dust collecting step. It is configured to remove volatile substances from dust collected in the process.

  According to such a configuration, the volatile substance is removed from the dust collected in the first dust collection process by being configured to remove the volatile substance from the dust collected in the second dust collection process. It is possible to further reduce the amount of volatile substances returned to the firing facility.

  Specifically, in the second dust collection step, dust having a finer particle size than that in the first dust collection step is collected. For this reason, the content of the volatile substance in the dust collected in the second dust collection process is larger than the content of the volatile substance in the dust collected in the first dust collection process. For this reason, more volatile substances will be removed from dust by performing a volatile substance removal process with respect to the dust collected by a 2nd dust collection process. Thereby, the quantity of the volatile substance supplied to the baking facility together with the dust is reduced, and the quantity of the volatile substance contained again in the exhaust gas is reduced. For this reason, the density | concentration of the volatile substance in waste gas can be reduced to the desired value.

  As described above, since the amount of the volatile substance supplied to the firing facility together with the dust is adjusted by performing the volatile substance removing process on the dust collected in the second dust collecting process, the cement The amount of volatile substances circulating in the production facility is adjusted as necessary. Thereby, the density | concentration of the volatile substance in the waste gas after a dust collection process can be maintained at the desired value.

  Moreover, the method according to the present invention can be applied universally to a cement manufacturing facility equipped with an electric dust collector. For this reason, for example, the method according to the present invention can be applied universally to a cement manufacturing facility including a vertical raw material mill, a cement manufacturing facility including a combination of a rotary dryer and a tube mill, and the like. .

  The gas treatment method of the present invention further includes a concentration measurement step for measuring the concentration of volatile substances in the exhaust gas after the dust collection step, and an applied voltage to the electric dust collector based on the measurement result in the concentration measurement step. It is preferable to adjust the dust collection amount of the dust collected in the second dust collection step by adjusting.

  Here, adjustment of the applied voltage to the electrostatic precipitator means that the applied voltage is changed continuously or intermittently, or the charge of the electrostatic precipitator is temporarily stopped or restarted, or these Means a combination of

  According to such a configuration, the amount of dust collected in the first dust collection step is adjusted by adjusting the voltage applied to the electric dust collector. Specifically, in the electrostatic precipitator, by reducing the voltage from a predetermined applied voltage, among the dust collected by the electrostatic precipitator, dust having a relatively fine particle size is not collected. In addition, by stopping charging of the electric dust collector, dust collection by the electric dust collector is stopped. That is, by reducing the voltage applied to the electrostatic precipitator or stopping the charging of the electrostatic precipitator, the amount of dust collected by the electrostatic precipitator is reduced.

  Conversely, by increasing the applied voltage from a lowered state, dust with a relatively fine particle size is also collected. Moreover, dust collection by the electric dust collector is resumed by resuming charging of the electric dust collector. That is, increasing the voltage applied to the electrostatic precipitator or restarting charging of the electrostatic precipitator increases the amount of dust collected by the electrostatic precipitator.

  In this way, by adjusting the voltage applied to the electric dust collector, the amount of dust collected in the first dust collecting step is adjusted, and thus the amount of dust supplied to the second dust collecting step is adjusted. Thereby, the supply amount of the dust supplied to the volatile substance removal step through the second dust collection step is also adjusted.

  And the amount of dust collection in a 2nd dust collection process is adjusted by adjusting the voltage applied to an electric dust collector based on the measurement result in a density | concentration measurement process. Specifically, when the measurement result of the concentration measurement process exceeds a desired value, the voltage applied to the electrostatic precipitator is reduced or the charging of the electrostatic precipitator is temporarily stopped, Increase the amount of dust supplied to the dust collection process to increase the amount of dust collected in the second dust collection process. As a result, the amount of dust supplied to the volatile substance removing step through the second dust collecting step is increased.

  In particular, among dusts collected in the first dust collection process and not supplied to the volatile substance removal process, volatile substances are likely to adhere (precipitate) to dust having a relatively fine particle size. As the dust is supplied to the volatile substance removal step, more volatile substances are removed from the dust. For this reason, the quantity of the volatile substance supplied to a baking facility with dust reduces, and the quantity of the volatile substance contained again in waste gas reduces. Thereby, the density | concentration of the volatile substance in waste gas can be reduced to the desired value.

  In addition, when the measurement result in the concentration measurement process falls below the desired value, supply to the second dust collection process by increasing the voltage applied to the electrostatic precipitator or restarting the electrostatic precipitator. The amount of dust that is generated is reduced, and the amount of dust that is supplied from the first dust collection process to the firing facility is increased.

  As described above, by adjusting the voltage applied to the electrostatic precipitator based on the measurement result in the concentration measurement process, the supply amount of dust (particularly, dust having a relatively fine particle size) to the volatile substance removal process is adjusted. Therefore, the amount of volatile substances circulating in the cement production facility is adjusted within a necessary range. Thereby, the density | concentration of the volatile substance in the waste gas after a dust collection process can be maintained at the desired value.

  The method according to the present invention further includes a particle size measurement step for measuring the particle size distribution of the dust collected in the second dust collection step, based on the measurement result in the concentration measurement step and the measurement result in the particle size measurement step. The voltage applied to the electrostatic precipitator is preferably adjusted.

  According to such a configuration, the concentration of volatile substances in the exhaust gas after the dust collection process is adjusted by adjusting the voltage applied to the electric dust collector based on the measurement result in the concentration measurement process and the measurement result in the particle size measurement process. It can be easily grasped.

  Specifically, as described above, the amount of dust supplied to the second dust collection process changes by adjusting the voltage applied to the electric dust collector. Accordingly, the particle size distribution of the dust collected in the second dust collection process changes. That is, by measuring the particle size distribution of the dust collected in the second dust collection step in the particle size measurement step, it is possible to grasp the change in the amount of dust supplied to the volatile substance removal step.

  As a result, even if there is a time lag in the concentration change of volatile substances in the exhaust gas after the dust collection process with respect to the adjustment (change) of the voltage applied to the electric dust collector, Thus, the concentration of volatile substances in the exhaust gas after the dust collection process can be grasped. For this reason, the density | concentration of the volatile substance in the waste gas after a dust collection process can be maintained easily.

  Moreover, it is preferable to further include a supply amount adjusting step of adjusting the amount of dust supplied to the volatile substance removing step based on the measurement result in the concentration measuring step.

  According to such a configuration, a necessary amount of dust is supplied to the volatile substance removing step so that the volatile substance concentration of the exhaust gas after the dust collecting step becomes a predetermined value by further including a supply amount adjusting step. Can do. For this reason, it can prevent that a volatile substance removal process is performed excessively.

  A gas treatment apparatus according to the present invention includes a dust collection facility for collecting dust in exhaust gas discharged from a firing facility for firing cement raw material, and fires at least a part of the dust collected by the dust collection facility. A gas treatment facility configured to be able to supply to the facility, further comprising a volatile substance removal facility for removing volatile substances from the dust collected by the dust collection facility, the dust collection facility comprising an electric dust collector Using a first dust collecting facility for collecting dust from exhaust gas and a second dust collecting facility for collecting dust from exhaust gas discharged from the first dust collecting facility, wherein the volatile substance removing facility is The second dust collection facility is configured to remove volatile substances from the dust collected.

  Further, it further comprises a concentration measurement facility for measuring the concentration of volatile substances in the exhaust gas discharged from the dust collection facility, and by adjusting the voltage applied to the electric dust collector based on the measurement result in the concentration measurement facility, It is preferable that the dust collection amount of the dust collected by the second dust collection facility is adjustable.

  Further, the apparatus further comprises a particle size measurement facility for measuring the particle size distribution of dust collected by the second dust collection facility, and applied to the electric dust collector based on the measurement result in the concentration measurement facility and the measurement result in the particle size measurement facility. It is preferable that the voltage is adjustable.

  Moreover, it is preferable to further include a supply amount adjusting facility for adjusting the amount of dust supplied to the volatile substance removing facility based on the measurement result in the concentration measuring facility.

  As described above, according to the present invention, volatile substances can be efficiently removed from the dust separated from the exhaust gas discharged from the cement firing facility and supplied to the firing facility, and circulated in the cement manufacturing facility. The content of the volatile substance to be maintained can be maintained at a desired value in the long term, and can be used for a general purpose in a cement manufacturing facility.

The schematic diagram which shows roughly the manufacturing equipment of the cement clinker used for the gas processing method in embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG.

  The gas processing method and the gas processing facility 1 according to the present embodiment are exhaust gas generated in a cement clinker manufacturing facility (hereinafter also referred to as cement manufacturing facility) (specifically, exhaust gas discharged from a firing facility A described later). ) From which dust can be collected. In addition, the gas processing method and the gas processing facility 1 according to the present embodiment are used when a cement clinker is manufactured using a cement raw material or a calcinated fuel containing a volatile substance. Volatile substances are volatilized at a predetermined temperature and are deposited when the temperature falls below such temperature, and examples thereof include heavy metals such as mercury and thallium, chlorides of these heavy metals, and organic compounds such as toluene and benzene. It is done.

  The gas processing facility 1 according to the present embodiment constitutes a part of a cement clinker manufacturing facility (hereinafter also referred to as a cement manufacturing facility). Specifically, the cement manufacturing facility includes a firing facility A for firing the cement raw material (specifically, a kiln A1 for firing the cement raw material to form a cement clinker, and a cement raw material before being supplied to the kiln A1). Preheating equipment A2) for preheating, storage equipment A3 for storing cement raw material supplied to the firing equipment A (specifically, preheating equipment A2), and firing equipment A (specifically, kiln) Pretreatment facility A4 in which the exhaust gas discharged from A1 and the preheating facility A2) is pretreated before being supplied to the gas treatment facility 1 (specifically, sedimentation that separates dust having a relatively large particle size from the exhaust gas) Chamber A4a, a stabilizer A4b) for adjusting the temperature of the exhaust gas and separating dust having a relatively large particle size from the exhaust gas, and configured to collect dust having a relatively small particle size. A scan processing equipment 1 supplies a cement raw material supply equipment A5 (e.g., raw mill) and, and an exhaust system for discharging exhaust gas to the atmosphere A6 (chimney, etc.).

  In addition, the dust in the exhaust gas supplied to the gas treatment facility 1 is a vertical raw material mill that constitutes the raw material supply facility A5 in addition to the dust generated in the firing facility A (for example, derived from cement raw material or calcined fuel). It may contain dust generated by the like. Specifically, at least a part of the exhaust gas discharged from the settling chamber A4a is supplied to the vertical raw material mill when the vertical raw material mill constituting the raw material supply facility A5 is operating. For this reason, in addition to the dust discharged from the firing facility A, the dust generated in the vertical raw material mill is also contained in the exhaust gas. For this reason, the exhaust gas supplied to the gas treatment facility 1 may contain dust derived from cement raw material or calcined fuel and dust generated in the vertical raw material mill constituting the raw material supply facility A5. .

  The gas treatment facility 1 includes a dust collection facility 2 that collects dust in the exhaust gas discharged from the firing facility A. And it is comprised so that at least one part of the dust collected by this dust collection equipment 2 can be supplied to the baking equipment A. FIG. Specifically, the gas treatment facility 1 is configured to be able to supply dust collected by the dust collection facility 2 to the storage facility A3, and to be able to supply dust to the firing facility A through the storage facility A3. Composed.

  The dust collection facility 2 is configured to be able to collect dust having a particle size finer than the dust separated from the exhaust gas in the pretreatment facility A4. In addition, the dust collection facility 2 is a first dust collection facility (specifically, an electric dust collection device) configured to collect dust having a relatively coarse particle size among the dust in the exhaust gas supplied to the dust collection facility 2. A dust collector 2a, and a second dust collector (specifically, a bag filter) 2b that collects dust in the exhaust gas supplied to the dust collector 2 with a relatively fine particle size.

  In addition, the gas treatment facility 1 includes a volatile substance removal facility 3 that removes volatile substances from dust collected by the dust collection facility 2, and a dust collection facility 2 (specifically, a second dust collection facility 2b). And a concentration measurement facility 4 for measuring the concentration of volatile substances in the exhaust gas discharged from the exhaust gas.

  The gas treatment facility 1 includes a particle size measurement facility 2c that measures the particle size distribution of dust collected by the second dust collection facility, and a supply amount adjustment facility that adjusts the amount of dust supplied to the volatile substance removal facility 3. 2d and a volatile material recovery facility 3a that recovers the volatile material removed by the volatile material removal facility 3.

  In the cement manufacturing facility having the above-described configuration, exhaust gas is generated when the cement raw material is fired in the kiln A1. The kiln A1 is not particularly limited, and for example, a dry kiln, a wet kiln, a lepole kiln, an SP kiln, an NSP kiln, a fluidized bed kiln, or the like can be used. In the generated exhaust gas, the volatile substances contained in the cement raw material and the fired fuel are contained in a volatilized state.

  Such exhaust gas is discharged from the kiln A1, and then passes through the preheating facility A2 (the calcining furnace A2b and the preheater A2a). At this time, the cement raw material supplied to the preheating facility A2 (specifically, the preheater A2a and the calcining furnace A2b) exchanges heat with the exhaust gas, and the temperature of the exhaust gas decreases. The temperature of the exhaust gas discharged from the firing facility A (specifically, the preheating facility A2) is not particularly limited, and is preferably 450 ° C. or less, for example, 400 ° C. or less. preferable. As preheating equipment A2, what is equipped with preheater A2a which preheats a cement raw material, and calcining furnace A2b which calcines the preheated cement raw material can be used. The preheater A2a is not particularly limited, and a new suspension preheater in which a plurality of cyclones are connected in multiple stages can be used.

  The exhaust gas discharged from the firing facility A (specifically, the preheating facility A2, more specifically, the preheater A2a) is supplied to the pretreatment facility A4. The temperature of the exhaust gas immediately before being supplied to the pretreatment facility A4 (specifically, the settling chamber A4a) is not particularly limited, but is preferably 400 ° C or lower, and 350 ° C or lower. Is more preferable.

  The exhaust gas supplied to the pretreatment facility A4 is first supplied to the settling chamber A4a. In the sedimentation chamber A4a, among the dust in the exhaust gas supplied to the pretreatment facility A4, dust having a relatively coarse particle diameter is collected. Specifically, in the sedimentation chamber A4a, for example, dust having a particle size of 0.5 mm or more as measured by a laser diffraction particle size distribution meter is preferably collected, and dust having a particle size of 0.1 mm or more is preferably collected. Is more preferably collected.

  The exhaust gas discharged from the settling chamber A4a is supplied to the stabilizer A4b when the raw material mill of the raw material supply facility A5 is stopped. In the stabilizer A4b, the temperature and moisture content of the exhaust gas are adjusted by passing the exhaust gas, and dust having a particle size smaller than that of the dust separated from the exhaust gas in the settling chamber A4a is separated from the exhaust gas.

  The dust separated from the exhaust gas in the pretreatment facility A4 (specifically, the settling chamber A4a and the stabilizer A4b) is supplied to the storage facility A3 and stored. The dust is supplied to the firing facility A (specifically, after being supplied to the preheating facility A2 and then to the kiln A1) as a cement material together with the cement material supplied from the material supply facility A5 to the storage facility A3. The That is, at least a part of the dust in the exhaust gas is discharged from the firing facility A and then returned to the firing facility A as a cement material.

  The exhaust gas discharged from the pretreatment facility A4 (specifically, the stabilizer A4b) is supplied to the gas treatment facility 1. The temperature of the exhaust gas immediately before being supplied to the gas treatment facility 1 is not particularly limited, but is preferably 200 ° C. or less, and more preferably 150 ° C. or less. Moreover, it is preferable that it is 50 degreeC or more, and it is more preferable that it is 100 degreeC or more.

  The exhaust gas supplied to the gas treatment facility 1 is supplied to the dust collection facility 2. Thereby, the dust in exhaust gas is collected (dust collection process). Specifically, the exhaust gas supplied to the gas treatment facility 1 is first supplied to the first dust collection facility (electric dust collector) 2a. In the first dust collection facility (electric dust collector) 2a, among the dust in the exhaust gas supplied to the gas treatment facility 1, dust having a relatively coarse particle size is collected (first dust collection step). As the particle size of the dust collected by the first dust collecting equipment 2a, for example, dust having a particle size of 100 μm or more as measured by a laser diffraction particle size distribution meter is preferably collected. Is more preferably collected.

  The exhaust gas discharged from the first dust collection facility (electric dust collector) 2a is supplied to the second dust collection facility (bag filter) 2b. The temperature of the exhaust gas immediately before being supplied to the second dust collection facility (bag filter) 2b is preferably 200 ° C. or less, and more preferably 150 ° C. or less. In the second dust collection facility (bag filter) 2b, dust having a relatively fine particle size is collected from the dust in the exhaust gas supplied to the gas processing facility 1 (second dust collection step). As the particle size of the dust collected by the second dust collecting equipment 2b, for example, dust having a particle size of 10 μm or more measured by a laser diffraction particle size distribution meter is preferably collected, and 0.1 μm or more. More preferably, the dust is collected.

  Dust collected by the gas treatment facility 1 (specifically, the electric dust collector 2a and the bag filter 2b) is supplied to the storage facility A3 and stored. The dust is supplied to the firing facility A (specifically, after being supplied to the preheating facility A2 and then to the kiln A1) as a cement material together with the cement material supplied from the material supply facility A5 to the storage facility A3. The That is, at least a part of the dust in the exhaust gas is discharged from the firing facility A and then returned to the firing facility A as a cement raw material. Thus, in the cement manufacturing facility according to the present embodiment, dust in the exhaust gas is also used as a cement raw material.

  On the other hand, the exhaust gas discharged from the dust collection facility 2 (specifically, the second dust collection facility 2b) is evacuated by the concentration measurement facility 4 before being discharged into the atmosphere via the exhaust facility A6. The content is measured (concentration measurement step). Further, the measurement with the concentration measuring equipment 4 may be continuous or intermittent. Further, a part of the exhaust gas discharged from the dust collection facility 2 (specifically, the second dust collection facility 2b) may be sent to the raw material supply facility A5 and used to dry the cement raw material. .

  Here, the temperature of the exhaust gas discharged from the firing facility A decreases before reaching the gas processing facility 1. At this time, volatile substances contained in the exhaust gas in a volatilized state adhere (deposit) to the dust in the exhaust gas due to the temperature decrease of the exhaust gas. In particular, among dusts supplied to the gas treatment facility 1, volatile substances are likely to adhere (precipitate) to dust having a relatively fine particle size. For this reason, after at least a part of the dust collected in the dust collection equipment 2 (dust collection process) is supplied to the volatile substance removal equipment 3 (volatile substance removal process) and volatile substances are removed, It is supplied to the storage facility A3. Specifically, among the dust supplied to the gas treatment facility 1, the dust is collected by the second dust collection facility (bag filter) 2b (second dust collection step) that collects dust having a relatively small particle diameter. Dust is supplied to the volatile substance removal equipment 3 (volatile substance removal process).

  The supply amount of dust to the volatile substance removal equipment 3 is adjusted by the supply quantity adjustment equipment 2d (supply quantity adjustment process). The supply amount adjusting equipment 2d is configured to supply a part of the dust collected by the second dust collecting equipment (bag filter) 2b to the volatile substance removing equipment 3 and supply the other to the storage equipment A3. The The supply amount adjusting facility 2d is configured to adjust the dust supply amount based on the concentration of volatile substances in the exhaust gas discharged from the second dust collecting facility 2b. A required amount of dust is supplied to the volatile substance removal equipment 3 (volatile substance removal process) so that the volatile substance concentration of the exhaust gas (discharged from the dust collection equipment 2) after the dust collection process becomes a predetermined value. Therefore, it is possible to prevent the process (volatile substance removing step) in the volatile substance removing equipment 3 from being performed excessively.

  In the present embodiment, a heating device can be used as the volatile substance removal facility 3. In the heating device, the supplied dust is heated to a temperature equal to or higher than the volatilization temperature of the volatile substance, thereby volatilizing and removing the volatile substance from the dust. Volatile substances removed by the volatile substance removal equipment 3 (volatile substance removal process) are collected by the volatile substance collection equipment 3a. For example, when the volatile substance is mercury, a volatile substance recovery facility 3a that uses adsorption by an activated carbon tower or absorption of an oxidizing solution can be used.

  On the other hand, the dust collected by the first dust collection equipment (electric dust collector) 2a has a coarser particle size than the dust collected by the second dust collection equipment (bag filter) 2b, so that volatile substances are attached. (Precipitation) is small. For this reason, the dust collected by the first dust collection facility (electric dust collector) 2a may be supplied to the storage facility A3 without being supplied to the volatile substance removal facility 3.

  In the gas treatment method according to the present invention, the voltage applied to the electric dust collector (first dust collecting equipment) 2a is adjusted based on the measurement result in the concentration measuring equipment 4 (concentration measuring step). Here, adjustment of the applied voltage to the electrostatic precipitator 2a is to change the applied voltage continuously or intermittently, or to temporarily stop or restart charging of the electrostatic precipitator, or It means a combination of these.

  By adjusting the voltage applied to the electric dust collector 2a, the amount of dust collected in the first dust collecting step (first dust collecting equipment 2a) is adjusted. Specifically, in the electric dust collector 2a, by reducing the voltage from a predetermined applied voltage, among the dust collected by the electric dust collector 2a, dust having a relatively fine particle size is not collected. Further, by stopping charging of the electrostatic precipitator 2a, dust collection by the electrostatic precipitator 2a is stopped. That is, by reducing the voltage applied to the electrostatic precipitator 2a or stopping the charging of the electrostatic precipitator 2a, the amount of dust collected by the electrostatic precipitator 2a is reduced.

  Conversely, by increasing the applied voltage from a lowered state, dust with a relatively fine particle size is also collected. Moreover, the dust collection in the electric dust collector 2a is restarted by restarting the charging of the electric dust collector 2a. That is, increasing the voltage applied to the electrostatic precipitator 2a or resuming the charging of the electrostatic precipitator 2a increases the amount of dust collected by the electrostatic precipitator 2a.

  In this way, by adjusting the voltage applied to the electric dust collector 2a, the amount of dust collected in the first dust collecting step (electric dust collector 2a) is adjusted, so the second dust collecting step (second dust collecting equipment 2b). ) Is adjusted. Thereby, the supply amount of the dust supplied to the volatile substance removal process (volatile substance removal equipment 3) through the second dust collection process (second dust collection equipment 2b) is adjusted.

  Then, by adjusting the voltage applied to the electrostatic precipitator 2a based on the measurement result in the concentration measurement step (concentration measurement facility 4), dust collection in the second dust collection step (second dust collection facility 2b) is performed. The amount is adjusted. Specifically, when the measurement result of the concentration measurement step (concentration measurement equipment 4) exceeds a desired value, the voltage applied to the electrostatic precipitator 2a is reduced, or the charging of the electrostatic precipitator 2a is temporarily stopped. By increasing the amount of dust supplied to the second dust collection step (second dust collection facility 2b), the amount of dust collected in the second dust collection step (second dust collection facility 2b) is increased. . This increases the amount of dust supplied to the volatile substance removal step through the second dust collection step (second dust collection facility 2b).

  In particular, volatile substances are contained in dust having a relatively fine particle diameter that has not been supplied to the volatile substance removing step (volatile substance removing equipment 3) after being collected by the first dust collecting equipment (electric dust collector) 2a. Since it tends to adhere (deposit), more volatile substances are removed from the dust by supplying such dust to the volatile substance removing step (volatile substance removing equipment 3). . For this reason, the amount of volatile substances supplied (returned) together with dust to the firing facility is reduced, and the amount of volatile substances contained again in the exhaust gas is reduced. Thereby, the density | concentration of the volatile substance in waste gas can be reduced to the desired value.

  Moreover, when the measurement result in the concentration measurement process (concentration measurement equipment 4) falls below a desired value, the voltage applied to the electrostatic precipitator 2a is increased, or charging of the electrostatic precipitator 2a is resumed. The amount of dust supplied to the second dust collection step (second dust collection facility 2b) is decreased, and the amount of dust supplied from the first dust collection facility (electric dust collector) 2a to the firing facility A is increased.

  As described above, by adjusting the applied voltage to the electrostatic precipitator 2a based on the measurement result in the concentration measurement step (concentration measurement facility 4), dust (volatile material removal facility 3) dust ( In particular, since the supply amount of dust having a relatively fine particle size is adjusted, the amount of volatile substances circulating in the cement manufacturing facility is adjusted within a necessary range. Thereby, the density | concentration of the volatile substance in the waste gas (discharged from the dust collection equipment 2) after a dust collection process is maintainable to the desired value.

  In addition, the method according to the present invention can be applied universally to a cement manufacturing facility including the electric dust collector 2a. For this reason, for example, the method according to the present invention can be applied universally to a cement manufacturing facility including a vertical raw material mill, a cement manufacturing facility including a combination of a rotary dryer and a tube mill, and the like. .

  In this embodiment, the applied voltage to the electrostatic precipitator may be adjusted based on the measurement result in the concentration measurement step (concentration measurement facility 4) and the measurement result in the particle size measurement step (particle size measurement facility 2c). Good.

  Thereby, the density | concentration of the volatile substance in the waste gas (discharged from the dust collection equipment 2) after a dust collection process can be grasped | ascertained easily.

  Specifically, as described above, the amount of dust supplied to the second dust collecting step (second dust collecting equipment 2b) is changed by adjusting the voltage applied to the electric dust collector 2a. For this reason, the particle size distribution of the dust collected in the second dust collection step (second dust collection equipment 2b) changes. That is, by measuring the particle size distribution of the dust collected in the second dust collection step (second dust collection facility 2b) in the particle size measurement step (particle size measurement facility 2c), the volatile substance removal step (volatile substance removal) Changes in the amount of dust supplied to the equipment 3) can be grasped.

  This is a case where a time lag occurs in the concentration change of the volatile substance in the exhaust gas (discharged from the dust collection facility 2) after the dust collection process with respect to the adjustment (change) of the applied voltage to the electric dust collector 2a. However, based on the measurement result in the particle size measurement step (particle size measurement facility 2c), the concentration of the volatile substance in the exhaust gas after being collected (discharged from the dust collection facility 2) can be grasped. For this reason, the density | concentration of the volatile substance in the waste gas (discharged from the dust collection equipment 2) after a dust collection process can be maintained easily.

  In addition, the gas processing method and gas processing apparatus which concern on this invention are not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention. Further, the configurations and methods of the plurality of embodiments described above may be arbitrarily adopted and combined (even if the configurations and methods according to one embodiment are applied to the configurations and methods according to other embodiments). Of course.

  In the said embodiment, although a bag filter is used in the 2nd dust collection process and the 2nd dust collection equipment 2b, it is not limited to this, Other dust collection equipment, for example, an electric dust collector, is used. May be. Specifically, an electric dust collector may be used as the second dust collection facility 2b. Alternatively, as the electric dust collector used as the first dust collection equipment 2a in the above embodiment, a plurality of charging chambers are provided, and each charging chamber is configured such that the applied voltage can be adjusted independently. Also good. In this case, the first dust collection step may be performed in one charging chamber of the electric dust collector, and the second dust collection step may be performed in another charging chamber.

  Moreover, in the said embodiment, although equipped with the particle size measurement equipment 2c (particle size measurement process) and the supply amount adjustment equipment 2d (supply amount adjustment process), it is not limited to this, either of these, or The configuration may be such that both are not provided.

  DESCRIPTION OF SYMBOLS 1 ... Gas processing equipment, 2 ... Dust collection equipment, 2a ... First dust collection equipment, 2a ... Electric dust collector, 2b ... Second dust collection equipment, 2b ... Bag filter, 2c ... Particle size measurement equipment, 2d ... Supply amount adjustment equipment DESCRIPTION OF SYMBOLS 3 ... Volatile substance removal equipment, 3a ... Volatile substance collection equipment, 4 ... Concentration measurement equipment, A ... Firing equipment, A1 ... Kiln, A2 ... Preheating equipment, A2a ... Preheater, A2b ... Calciner, A3 ... Storage equipment, A4 ... Pretreatment equipment, A4a ... Settling chamber, A4b ... Stabilizer, A5 ... Raw material supply equipment, A6 ... Exhaust equipment

Claims (8)

A gas treatment method comprising a dust collection step for collecting dust in exhaust gas discharged from a firing facility for firing cement raw material, and supplying at least a part of the dust collected in the dust collection step to the firing facility as cement raw material Because
A volatile substance removing step of removing volatile substances from the dust collected in the dust collecting step;
The dust collection step includes a first dust collection step of collecting dust from exhaust gas using an electric dust collector, and a second dust collection step of collecting dust from exhaust gas after the first dust collection step,
The gas processing method, wherein the volatile substance removing step is configured to remove volatile substances from the dust collected in the second dust collecting step.   The method further comprises a concentration measurement step for measuring the concentration of volatile substances in the exhaust gas after the dust collection step, and adjusting the applied voltage to the electric dust collector based on the measurement result in the concentration measurement step, thereby providing the second dust collection The gas treatment method according to claim 1, wherein the amount of dust collected in the process is adjusted.   The method further comprises a particle size measurement step for measuring the particle size distribution of the dust collected in the second dust collection step, and based on the measurement result in the concentration measurement step and the measurement result in the particle size measurement step, the applied voltage to the electric dust collector is The gas treatment method according to claim 2, wherein the gas treatment method is adjusted.   The gas processing method according to claim 2, further comprising a supply amount adjustment step of adjusting a supply amount of dust supplied to the volatile substance removal step based on a measurement result in the concentration measurement step. Gas configured to collect dust in exhaust gas discharged from a firing facility for firing cement raw material and configured to supply at least a part of the dust collected by the dust collection facility to the firing facility A processing facility,
A volatile substance removing facility for removing volatile substances from the dust collected by the dust collecting facility;
The dust collection facility includes a first dust collection facility that collects dust from exhaust gas using an electric dust collector, and a second dust collection facility that collects dust from exhaust gas discharged from the first dust collection facility. And
The volatile substance removing equipment is configured to remove volatile substances from dust collected by the second dust collecting equipment.   A concentration measuring facility for measuring a concentration of a volatile substance in the exhaust gas discharged from the dust collecting facility, and adjusting a voltage applied to the electric dust collector based on a measurement result in the concentration measuring facility; 6. The gas processing facility according to claim 5, wherein the dust collection amount of dust collected by the dust collection facility is configured to be adjustable.   The apparatus further comprises a particle size measuring facility for measuring the particle size distribution of dust collected by the second dust collecting facility, and the applied voltage to the electric dust collector is determined based on the measurement result in the concentration measuring facility and the measurement result in the particle size measuring facility. The gas processing facility according to claim 6, wherein the gas processing facility is adjustable.   The gas processing facility according to claim 6 or 7, further comprising a supply amount adjustment facility for adjusting a supply amount of dust supplied to the volatile substance removal facility based on a measurement result in the concentration measurement facility.

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